Experimental infusion phlebitis: tolerance osmolality of peripheral venous endothelial cells

This study aimed to determine the osmolality that peripheral venous endothelial cells can tolerate and to clarify the relationship between tolerance osmolality and duration of infusion. Nutrient solutions of 539–917 mOsm/kg, prepared to have no acidic effect, were infused into rabbit ear veins, and the veins were examined histopathologically. In each experiment of 8-, 12-, or 24-h infusion, the higher osmolality solutions caused some phlebitic changes, such as loss of venous endothelial cells, inflammatory cell infiltration, and edema; however, the lowest osmolality solution caused few changes. Infusion of 120 mL/kg of 814 mOsm/kg solution caused phlebitis at 5 or 10 mL · kg−1 · h−1, however, the same volume of the same solution scarcely caused phlebitis at 15 mL · kg−1 · h−1 because of the shortened infusion duration. These results suggest that the tolerance osmolality of peripheral venous endothelial cells with poor blood flow is about 820 mOsm/kg for 8 h, 690 mOsm/kg for 12 h, and 550 mOsm/kg for 24 h, and that the tolerance osmolality falls as the duration of infusion increases. In conclusion, hypertonic solutions should be infused at as high a rate as is clinically acceptable and compatible with nutrient bioavailability because increasing the infusion rate reduces the duration of infusion and phlebitis.